well that's weird: when I said simplex collects users' data, I meant «when you use application SimpleXChat, it sends anonymized diagnostics about the use to improve your usage experience» — yet now I cannot find any proofs of that not. I was sure I read it myself in their privacy policy. Huh...

Anyway, yes, official servers do collect some statistics (which may be somewhat dangerous: https://www.nature.com/articles/s41467-019-10933-3 — yet not too bad). I'm not sure if using own server won't identify you by centralizing all your connections, killing the main reason to use the app: when 100 (your) pseudonyms uses all one same small server, and no or almost no other people are using it, pseudonyms can clearly be identified as belonging to a one person, or am I wrong?